In many environments, it is important to support voice calling, including in networks where Long Term Evolution (LTE) is deployed. However, LTE does not support voice calling over legacy networks, instead providing voice capability via its own standard, Voice over LTE (VoLTE). There is consequently a need for compatibility with legacy voice calling, including circuit-switched (CS) voice calling, that is currently met imperfectly, typically by providing both a 2G/3G core network and a parallel LTE core network. As both networks have cumulative maintenance and operational expense (opex) requirements, the new network is significantly more expensive.
As well, with the requirement that wireless operators support all generations of radio technologies, and the expense of maintaining 2G, 3G, 4G and upcoming 5G infrastructures, operators have desired to transition their core infrastructure to remove legacy components and converge to a single IP core. This will help them move to all IP, an all-virtualized core network infrastructure and reduce not only capital expenditures (capex) but also operational expenditures (opex) significantly.